Electrolytic water heaters are known in which water, or other solutions, are heated by passing an electric current through the solution from one electrode to another, the electrodes being mounted to be in contact with the solution. Problems have been encountered, however, in the prior art electrolytic heaters.
One problem is that when ordinary tap water is used in an electrolytic heater, the conductivity of the tap water varies from one locality to another, and this produces design problems in the construction of the heaters due to the varying amount of heat produced by any given physical configuration as different tap water is used. Also, under normal circumstances, if chemicals, such as sodium chloride, sodium bicarbonate, or the like, are added to increase the conductivity of the tap water, difficulties are encountered in controlling the heating rate and boiling of the solution, since the heating rate is a function of the quantity of the added chemicals. Also, if the solution boils dry in the heater, the added chemicals, as well as minerals normally contained in the tap water, appear as deposited film on the inner surfaces of the wall of the housing of the heater, and these present cleaning problems.
Because of the foregoing, it is suggested in the heater of the present invention that distilled water be used, with a predetermined amount of sodium chloride added, so as to provide an electrically conductive solution which will be standard for all the heaters, wherever the heaters may be used.
Problems still arise in the construction of electrolytic water heaters, even when distilled water is used. For example, if the heating rate is controlled by limiting the area of the electrodes exposed to the solution in the heater, cavitation of the solution at the electrode contact surfaces often occurs, and this leads to arcing, electrode pitting, and a shortening of useful electrode life.
Cavitation of the solution at the electrodes, and its attendant deleterious effects, is obviated in the electrolytic heater of the present invention by the provision of two separate chambers in the heater housing, one for each electrode; the chambers being designed to hold the desired quantity of the solution which is to be heated. The two chambers are interconnected, as stated above, by means of an opening or channel in the wall between the chambers into which the liquid from the two chambers extends. This channel has reduced dimensions with respect to the dimensions of the chambers, and the boiling of the liquid occurs in the channel. This eliminates the generation of bubbles in the vicinity of the electrodes so that erosion effects are obviated.
In brief, the construction of the present invention, in which the two electrodes are mounted in separate chambers, and in which boiling of the solution occurs in an interconnecting channel or slot of reduced dimensions, removes the cavitation effects from the electrodes themselves, so that the electrodes are not subjected to erosion during the operation of the heater.
One use for the heater of the invention is for sterilizing soft contact lenses for the eyes. The lenses are placed in a separate receptacle which is filled with a saline solution, and the receptacle is inserted above the slot or channel in the common wall of the heater, the saline solution in the receptacle being heated by the steam produced by the boiling solution in the channels, so as to perform the desired reaction on the contact lenses in the receptacle.